Location: Haskell, OKAccident Number: CEN15LA258Date & Time: 06/06/2015, 1258 CDTRegistration: N535CTAircraft: FLIGHT DESIGN GMBH CTSWAircraft Damage: SubstantialDefining Event: Loss of engine power (partial)Injuries: 2 MinorFlight Conducted Under: Part 91: General Aviation - Personal On June 6, 2015, about 1258 central daylight time, a Flight Design CTSW, light-sport airplane, N535CT, preformed a forced landing shortly after departing the Haskell Airport (2K9), Haskell, Oklahoma. The pilot and a passenger received minor injuries, and the airplane was substantially damaged during the off-airport landing. The airplane was registered to KT Aviation LLC, of Wagoner, Oklahoma, and was operated by a private individual as a 14 Code of Federal Regulations Part 91 personal flight. Day visual meteorological conditions prevailed and a flight plan had not been filed. The flight originated from 2K9 and was destined for Hefner-Easley Airport (H68), Wagoner, Oklahoma, at the time of the accident.The pilot reported that they had flown from H68 to 2K9 earlier in the day. Prior to departing H68, he did a normal preflight inspection, with no discrepancies noted and about 28 gallons of automotive fuel.After starting engine at 2K9, the pilot noticed the engine gauges were normal, but the charging system had an inadequate output, so he shut down the engine. After consulting a mechanic, he restarted the engine about 1245, with normal engine and charging indications.During the initial climb from 2K9 about 500 to 600 feet above ground level, the engine starting "sputtering". The engine continued to run but not enough to maintain altitude. The pilot selected a field for the forced landing; various throttle settings failed to restore engine power and the choke was off. The airplane touched down in a muddy field and came to rest inverted.An on-scene wreckage examination found substantial damage to the airplane's fuselage and damage to the airplane's landing gear. Fuel quality checks of the on-board fuel and the fuel facility were satisfactory. The wreckage was moved to a different location and a post-accident examination of the engine was conducted. Further examination revealed no water or debris were noted in the gascolator, the engine's left and right carburetor float bowls contained clean fuel, the sparkplugs appeared normal, and ignition spark was verified. A test run of the engine was conducted. The engine was started and run at idle before running up to power; no problems were noted during the engine examination or test run.The airplane's EFIS (Electronic Fight Information System) and EMS (Engine Monitoring System), were removed for extraction of volatile memory (NVM). The memory in the EFIS was corrupted and no useful information could be obtained. The EMS contained an eight-minute recording of engine parameters for the accident flight. A review of the EMS data revealed the engine acceleration to high power, followed by fluctuations and a reduction in the engine rpms.The NTSB's Vehicle Recorder Division's full factual report is located in the public docket for this case.The closest weather reporting station was located at the Okmulgee Regional Airport Okmulgee, Oklahoma, about 17 miles southwest from the accident site. At 1255, the station recorded wind from 150 degrees at 3 knots, visibility 10 miles, scattered clouds at 4,700 ft agl, temperature 88° F, dew point 70° F, and an altimeter setting of 30.00 inches of mercury.The carburetor icing probability chart included in Federal Aviation Administration Special Airworthiness Information Bulletin No. CE-09-35, Carburetor Icing Prevention, indicated that the airplane was operating in an area that was associated with a serious risk of carburetor ice formation at glide power settings.Pilot InformationCertificate: Sport PilotAge: 56Airplane Rating(s): Single-engine LandSeat Occupied: LeftOther Aircraft Rating(s): NoneRestraint Used: 4-pointInstrument Rating(s): NoneSecond Pilot Present: YesInstructor Rating(s): NoneToxicology Performed: NoMedical Certification: Sport Pilot NoneLast FAA Medical Exam:Occupational Pilot: NoLast Flight Review or Equivalent:Flight Time: (Estimated) 303 hours (Total, all aircraft), 254 hours (Total, this make and model), 254 hours (Pilot In Command, all aircraft), 10 hours (Last 90 days, all aircraft), 2 hours (Last 30 days, all aircraft) Pilot-Rated Passenger InformationCertificate: PrivateAge: 70Airplane Rating(s): Single-engine LandSeat Occupied: RightOther Aircraft Rating(s): NoneRestraint Used: 4-pointInstrument Rating(s): NoneSecond Pilot Present: YesInstructor Rating(s): NoneToxicology Performed: NoMedical Certification: Unknown NoneLast FAA Medical Exam: 01/01/1980Occupational Pilot: NoLast Flight Review or Equivalent: 01/01/1980Flight Time: (Estimated) 150 hours (Total, all aircraft), 0 hours (Total, this make and model)Aircraft and Owner/Operator InformationAircraft Make: FLIGHT DESIGN GMBHRegistration: N535CTModel/Series: CTSWAircraft Category: AirplaneYear of Manufacture: 2007Amateur Built: NoAirworthiness Certificate: Special Light-SportSerial Number: 07-05-01Landing Gear Type: UnknownSeats: 2Date/Type of Last Inspection: 09/14/2014, ConditionCertified Max Gross Wt.: 1320 lbsTime Since Last Inspection: 30 HoursEngines: 1 ReciprocatingAirframe Total Time: 543 Hours at time of accidentEngine Manufacturer: ROTAXELT: C126 installed, not activatedEngine Model/Series: 912 ULSRegistered Owner: KT5 AVIATION LLCRated Power: 80 hpOperator: On fileOperating Certificate(s) Held: None Meteorological Information and Flight PlanConditions at Accident Site: Visual ConditionsCondition of Light: DayObservation Facility, Elevation: KOKM, 720 ft mslDistance from Accident Site: 17 Nautical MilesObservation Time: 1755 UTCDirection from Accident Site: 234°Lowest Cloud Condition: Scattered / 4700 ft aglVisibility: 10 MilesLowest Ceiling:Visibility (RVR):Wind Speed/Gusts: 3 knots /Turbulence Type Forecast/Actual: /Wind Direction: 150°Turbulence Severity Forecast/Actual: /Altimeter Setting: 30 inches HgTemperature/Dew Point: 31°C / 21°CPrecipitation and Obscuration: No Obscuration; No PrecipitationDeparture Point: Haskell, OK (2K9)Type of Flight Plan Filed: UnknownDestination: WAGONER, OK (H68)Type of Clearance: NoneDeparture Time: 1258 CDTType of Airspace: Class GAirport InformationAirport: HASKELL (2K9)Runway Surface Type: AsphaltAirport Elevation: 588 ftRunway Surface Condition: DryRunway Used: 17IFR Approach: NoneRunway Length/Width: 3710 ft / 30 ftVFR Approach/Landing: Forced LandingWreckage and Impact InformationCrew Injuries: 1 MinorAircraft Damage: SubstantialPassenger Injuries: 1 MinorAircraft Fire: NoneGround Injuries: N/AAircraft Explosion: NoneTotal Injuries: 2 MinorLatitude, Longitude: 35.834167, -95.665833 (est)NTSB Identification: CEN15LA25814 CFR Part 91: General AviationAccident occurred Saturday, June 06, 2015 in Haskell, OKAircraft: FLIGHT DESIGN GMBH CTSW, registration: N535CTInjuries: 2 Minor.This is preliminary information, subject to change, and may contain errors. Any errors in this report will be corrected when the final report has been completed. NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.On June 6, 2015, about 1258 central daylight time, a Flight Design CTSW, light-sport airplane, N535CT, impacted terrain and was substantially damaged during an off-airport forced landing at Haskell Airport (2K9), Haskell, Oklahoma. The pilot and a passenger sustained minor injuries. The airplane was registered to KT Aviation LLC, of Wagoner, Oklahoma, and was operated by the pilot as a 14 Code of Federal Regulations Part 91 personal flight. Day visual meteorological conditions (VMC) prevailed and a flight plan had not been filed. At the time of the accident the airplane was departing from 2K9, and was destined for Hefner-Easley Airport (H68), Wagoner, Oklahoma.The pilot reported that during initial climb, while about 500 to 600 feet above ground level (agl), there was a sudden partial loss of engine power. The pilot was on left downwind leg when he executed a forced landing to a muddy field. The airplane came to rest inverted and the impact resulted in the almost complete separation of the empennage. There was a postimpact fuel spill, but there was no postimpact fire. Both occupants exited without assistance.An on-scene wreckage examination showed adequate fuel was on-board. Fuel quality checks of the on-board fuel and of the fuel facility were satisfactory. The wreckage was moved to a different location and a postaccident test run of the engine was satisfactory. Several avionics components containing non-volatile memory (NVM), including engine performance data, were removed from the wreckage for examination and an extraction of useful data is expected.

The closest official NWS reporting location was about 17 miles southwest from the accident site at Okmulgee Regional Airport (OKM) Okmulgee, Oklahoma. At 1255 the Automated Surface Observation System at OKM reported wind from 150 degrees at 3 knots, visibility 10 miles, scattered clouds at 4,700 feet agl, temperature 31 degrees Celsius (C), dew point 21 degrees C, and an altimeter setting of 30.00 inches of mercury.